I am one of the teachers on artsednet. It is a well known assumption
that because photography was able to stop a moment in time, that the
impressonists wanted to do that as well with their work, and avoid the
posed, artifice of the paintings that preceded their work. The
Impressionists attempted to render subjects in temporary and
instantaneous terms. Compare works of earlier painters with Monet,
Manet, Cezanne, Degas, Toulouse-Lautrec. Photographers and painters also
shared a preoccupation with "light" as well. AND, lastly, seeing people
through a fixed "lens" as compared through an emotional eye is also a
connecting factor.

What you may have to do for your research is this. First declare your
thesis statement. Then do research on the history of photography, then
on the Impressionists, and FIND the link between the two philosophies,
strategies, and outcomes of the photographers and artists....and then
make a conclusion.

The search engines I recommend are

Altavista ---use the advanced search
Dogpile
Askjeeves

Sometimes when doing research, YOU must make the connections because the
connections will not be stated in an obvious way. Which quite simply
means, you will probably not find a site that will say "Impressionism as
a result of the
development of photography". You MAY however find information on the
sites (AND DON'T FORGET YOUR PUBLIC/LOCAL COLLEGE LIBRARY, MOST OF US
USED THOSE EXTRODINARY BUILDINGS TO GET OUR DEGREES), where
photographers and painters of that time hung around together.